I really love the series.
That's the first book, by the way.
Nathaniel redeems himself in the last book, once he realizes what the Magicians are like.
It stands in stark contrast to what he idealized.
And Bartimaeus is just as funny and awesome in every book.
There's also a prequel, with Bartimaeus's time during the rule of Solomon.
“She'd become a governess. It was one of the few jobs a known lady could do. And she'd taken to it well. She'd sworn that if she did indeed ever find herself dancing on rooftops with chimney sweeps she'd beat herself to death with her own umbrella.”
― Hogfather